Showing posts with label Upwork > Electronics. Show all posts
Showing posts with label Upwork > Electronics. Show all posts
Monday, 12 October 2015
Monday, 5 October 2015
Semiconductor Electronics Test
Semiconductor Electronics Test
Two
identical germanium diodes are connected in series opposition. A 10V battery is
impressed upon this series arrangement. What will be the voltage across each
diode room temperature if the Zener breakdown voltage of each diode is 9.8V?
a. VD1= 0.2V , VD2
= 9.8V
b. VD1 = 10V , VD2
= 0V
c. VD1 = 0V , VD2
= 10V
d. VD1 = 9.8V , VD2
= 0.2V
Which one of the following is
Shockley's equation?
a. ID = IDSS
[1-VGS/VP]2
b. IDSS = ID
[1-VGS/VP]2
c. VP = IP
[1-VGS/IDSS]2
d. VGS = VP
[1-ID/IDSS]2
An
SCR combines the features of_____.
a. a
rectifier and an amplifier
b. a
rectifier and a transistor
c. a
rectifier and an oscillator
d. a
rectifier and an inverter
The
required gain of an amplifier for sustained oscillation in the wein bridge
oscillator is _____.
a. A 2
b. A 1
c. A 3
d. None
of the above
The
maximum value of AC voltage appearing across the secondary of a transformer in
a bridge circuit using a vacuum tube is 400 v. The peak inverse voltage of the
diode should be _____.
a. 200
v
b. 800
v
c. 400
v
d. 600
v
The
impedance of a parallel tuned circuit at resonance is _____.
a. 0
b. low
c. very
high
d. very
low
Which
of the following parameters is a measure of a vacuum tube's amplification
capability?
a. transresistance
b. impedance
c. conductance
d. transconductance
At
parallel resonance, a tuned circuit offers an impedance of _____.
a. C/LR
b. R/LC
c. L/CR
d. 2L/CR
Radio
frequencies have their range above _____.
a. 20KHZ
b. 50KHZ
c. 100KHZ
d. 200KHZ
The
stability factor of a biasing circuit is 10. What does it mean?
a. Ic
changes 10 times as munch as any change in Ico(leakage current)
b. Ib
changes 10 times as much as any change in Ico
c. Ie
change 10 times as munch as any change in Ico
The
maximum efficiency of a full wave rectifier is _____.
a. 40%
b. 81.2%
c. 90%
d. 99%
If
the collector supply voltage is 10v, the collector cut off voltage under D.C
conditions will be _____.
a. 5v
b. 10v
c. 20v
d. 30v
The
overall gain of a multistage amplifier is 140. When negative feedback is
applied, the gain is reduced to 17.5. The fraction of the output that is
feedback to the input will be _____.
a. 1/30
b. 1/20
c. 1/10
d. 1/5
The
complementary MOS(CMOS) uses _____.
a. only
n-channel devices in the circuit
b. only
p- channel devices in the circuit
c. both
n and p channel devices in the circuit
d. None
of the above
The
most commonly used semiconductor in solid state devices is _____.
a. germanium
b. carbon
c. silicon
d. phosphorus
Tuning
is generally accomplished by varying _____.
a. L(inductor)
b. C(capacitor)
c. both
L and C
d. R(resistor)
We have to match a 16-ohm speaker to
an amplifier so that the effective load resistance is 10 KΩ. What should be the
transformer turn ratio?
a. Np/Ns=50
b. Np/Ns=25
c. Np/Ns=75
d. Np/Ns=12.5
Which
coupling does the final stage of a multistage amplifier use?
a. direct
b. transformer
c. RC
d. None
of the above
Vacuum
tubes are _____.
a. linear
devices
b. non-linear
devices
c. both
linear and non-linear under different conditions
If in a transistor , Ic =
9.5mA , Ie = 10mA , the value of α will be _____.
a. 0.95
b. 10
c. 9.5
d. 0.095
The
range of LC oscillators is _____.
a. 20
HZ to 100KHZ
b. 10
HZ to 20 HZ
c. 100KHZ
to a few GHZ
A
three-stage amplifier has a first-stage voltage gain of 100, a second stage
voltage gain of 200 and a third stage gain of 400. The total voltage gain in db
will be _____.
a. 130 dB
b. 140
dB
c. 132
dB
d. 138
dB
Which
of the following conditions must a transistor fulfill to act as an amplifier?
a. Base-emitter
junction reverse biased and base-collector junction forward biased
b. Base-emitter
junction forward biased and base-collector junction reverse biased
c. Emitter-collector
junction forward biased and base- collector junction reverse biased
d. Base-collector
junction forward biased and emitter-collector junction reverse biased
Hartley
oscillator is _____.
a. an
RC oscillator
b. an
LC oscillator
c. a
Crystal oscillator
The
output characteristics of an FET closely resemble the plate characteristics of
a________ valve.
a. diode
b. triode
c. tetrode
d. pentode
The
slope of the D.C load line of a transistor circuit having a collector load Rc
is _____.
a. Rc
b. 1/Rc
c. -1/Rc
d. 2Rc
In
the d.c. equivalent circuit of a transistor amplifier , the capacitors are
regarded as _____.
a. Open
b. Short
c. Sometimes
open and sometimes short
d. Unchanged
In the collector feedback biasing, β
= 57 , RC = 1 kΩ , IB = 60µA and VCB = 4.5V.
The value of the stability factor will be _____.
a. 30.4
b. 32.9
c. 57
d. 4.5
If
the input to an integrating circuit is a square wave, the output will be _____.
a. triangular
b. rectangular
c. saw-tooth
d. spiked
Which
of the following configurations of a transistor is preferred as an amplifier?
a. common-collector
b. common-
base
c. common-emitter
d. None
of the above
A
D.C milliammeter connected to a half-wave rectifier supplying a maximum current
of 10mA will read _____.
a. 10
mA
b. 20
mA
c. 5 mA
d. 3.18
mA
A
triac can pass a portion of _____.
a. positive
half-cycle through the load
b. negative
half-cycle through the load
c. both
positive and negative half-cycles through the load
d. None
of the above
Which
one of the following is a non-feedback type oscillator?
a. Wein
bridge oscillator
b. Hartley
oscillator
c. UJT
relaxation oscillator
d. Colpitts
oscillator
If in a transistor IE =
10.5mA , IC = 10mA,the value of β will be _____.
a. 0.2
b. 200
c. 100
d. 20
A
transistor amplifier has 4v,2mA as the operating point. For faithful
amplification, the collector current due to signal alone should not exceed
_____.
a. 2mA
b. 1mA
c. 4mA
d. 8mA
A
vacuum tube conducts current _____.
a. from
the cathode to the anode
b. from
the anode to the cathode
c. in
both the above directions
d. alternately
in both directions
The input and output voltages of a
CE transistor amplifier are _____.
a. in phase
b. 90° out of phase
c. 180° out of phase
d. 120° out of phase
If
the input to a differentiating circuit is a square wave, the output will be
_____.
a. rectangular
b. spiked
c. triangular
d. sinusoidal
If a circuit of full-wave
centre-tapped rectifier with capacitor filter employs a load RL =
100Ω, and C = 1050µF and the frequency is 50HZ , what would be the ripple
factor?
a. 40%
b. 30%
c. 22%
d. 27%
Which of the following is used to
provide current in vacuum tubes?
a. protons
b. ions
c. electrons
d. neutrons
Saturday, 26 September 2015
Fiber Optics Test
Fiber Optics Test
For
a profile parameter (α)=1, the profile shape of refractive index for a graded
index fiber will be _____________.
a.
triangular
b.
parabolic
c. step
d.
circular
SOLITON
is a/an _____________.
a.
type of optical fiber
b.
optical source
c.
optical detector
d.
pulse traveling in optical fiber
The
fiber gyroscope is an _____________.
a.
Intrinsic fiber sensor
b.
Interferometer fiber sensor
c.
Extrinsic fiber sensor
d.
Extinction fiber sensor
The
output power of a LASER is greater than that of a LED because of _____________.
a.
stimulated emission
b.
spontaneous emission
c.
straight emission
d. None
of the above
A
multimode graded index fiber exhibits total pulse broadening of 0.2 µsec over a
distance of 10Km. Estimate the maximum possible bandwidth assuming that there
is no inter-symbol interference.
a. 5
MHZ
b. 2.5
MHZ
c.
10 MHZ
d. 1
MHZ
Dispersion
is low in the _____________.
a.
Multimode step index fiber
b.
Single mode step index fiber
c. Two
mode step index fiber
d. None
of the above
For
an ideal photo detector, the absorption coefficient must be _____________.
a. low
b. zero
c. one
d.
large
This
question is based upon the figure shown below
For
a step index fiber, relationship between numerical aperture (NA) and coupling
efficiency (ηc) is _____________.
a. a
b. b
c. c
d. d
Optical
bandwidth (OB) relates to electrical bandwidth (EB) when
a.
OB<EB
b.
OB=EB
c.
OB>EB
d.
OB≥EB
Superluminescent
LED's are preferred because of _____________.
a.
large spectral linewidth
b. a
directional output beam
c.
low output power
d.
small size
Germanium
photodiodes are generally not preferred in the optical fiber system because of
_____________.
a.
large current gain
b.
large voltage gain
c.
temperature dependence
d.
large dark current
The
refractive index is defined as the ratio of _____________.
a. the
velocity of light in a vacuum to the velocity of light in the medium
b.
the velocity of light in the medium to the velocity of sound in a vacuum
c. the
velocity of light in the medium to the velocity of light in a vacuum
Dispersion
is the lowest in a _____________.
a.
Multimode step-index fiber
b.
Multimode graded-index fiber
c.
Single-mode step-index fiber
d.
Silicon fiber
What
would the optical return loss (ORL) be defined as when r-fresnal reflection
occurs at a fiber-air interface?
a. ORL=
-10log10r
b.
ORL= -20log10r
c. ORL=
-30log10r
d. ORL=
-10loger
When
optical power is incident on the photo detector during the 0 bit period, then
the system is said to exhibit _____________.
a. a
non-zero extinction ratio
b. a
zero extinction ratio
c. an
infinity extinction ratio
d. an
infinity absorption ratio
Macro
bending losses in optical fibers can be reduced by designing the fibers with
_____________.
a. a
smaller refractive index difference
b. a
fiber glass
c. a
silica glass
d. a
larger refractive index difference
Which
phenomenon does not let light rays escape an optical fiber?
a.
Total internal reflection
b.
Total internal refraction
c.
Total internal diffraction
d.
Total internal attenuation
Rayleigh
scattering is a _____________.
a.
non-linear scattering
b. differential
scattering
c.
cumulative scattering
d.
linear scattering
IEEE
802.5 is a/an _____________.
a.
Ethernet
b.
Token bus
c.
Token ring
d.
Token star
For
a multimode optical graded index fiber, the profile parameter (α) will be equal
to:
a. ∞
b. Zero
c. 1
d. 2
Scattering
losses happen due to:
a. a
rise in temperature
b.
imperfections in glass manufacturing process
c.
humidity
d.
bending of fiber
Germanium
avalanche photodiodes can be used for _____________.
a.
longer wavelength operation
b.
shorter wavelength operation
c. low
output power operation
d.
minimum noise operation
FDDI
can support a data rate of
a.
10 Mbps
b. 10
Gbps
c. 100
Mbps
d. 1000
Mbps
Which
one of the following is a type of non-linear scattering?
a.
Stimulated Raman scattering (SRS)
b.
Rayleigh scattering
c. Mie
scattering
d.
Ultraviolet scattering
Dark
line defects (DLDs) occur when:
a.
non-radiative electron-hole recombination occurs
b.
mobile impurities are displaced into the active region of LASER
c. all
modes are not stabilized
d. all
modes are not polarized
The
vapor-phase deposition technique is used to produce _____________.
a.
fiber-rich glasses
b.
silica-rich glasses
c.
oxide-rich glasses
d.
carbonate-rich glasses
Light
emitting diodes (LED's) are:
a.
Monochromatic incoherent sources
b.
Monochromatic coherent sources
c.
Incandescent light sources
d.
None of the above
Silicon
reach through avalanche photodiodes has _____________.
a.
maximum absorption of photons
b.
maximum absorption of electrons
c.
maximum quantum efficiency
d.
minimum noise
Surface
emitter LEDs have high radiance because _____________.
a. a
hemisphere of n type GaAs is formed around a diffused p-type region
b. of
p-type diffusion into the n-type substrate
c. it
restricts the emission to a small active region
d.
of n-type diffusion into the p-type substrate
This
question is based upon the figure shown below
What
is signal attenuation in an optical fiber where P1=Input power and P0=Output
power
a. a
b. b
c. c
d. None
of the above
The
cutback technique is a/an _____________.
a.
attenuation measurement technique
b.
refractive index measurement technique
c.
impurity measurement technique
d.
frequency measurement technique
In
p-i-n photodiodes "i" stands for:
a.
Internal
b.
Intrinsic
c.
Impurity
d. None
of the above
What
is the relationship between refractive index (n1) of core and refractive index
(n2) of cladding for an optical fiber?
a. n1
< n2
b. n1 =
n2
c.
n1 <= n2
d. n1
> n2
Graded-index
fibers have:
a. a
constant refractive index in the core
b. a
variable refractive index in the cladding
c. a
variable refractive index in the core
d.
None of these
LED
is more suitable for analog transmission because of its _____________.
a.
linearity
b.
bandwidth (spectrum)
c.
modulation property
d.
output power
Homodyne
detection is used for _____________.
a.
incoherent systems
b.
incandescent systems
c.
coherent systems
d.
analog systems
The
rays which travel in a helical path through an optical fiber are called
_____________.
a.
refracted rays
b.
reflected rays
c.
infra-red rays
d.
skew rays
Mirrors
are placed in LASER optical sources to maintain conditions for _____________.
a.
incoherence
b.
amplification
c.
modulation
d.
coherence
Avalanche
photodiodes are _____________.
a. less
sensitive than simple photodiodes
b.
more sensitive than simple photodiodes
c.
cheaper than simple photodiodes
d. less
complex in structure than simple photodiodes
Dark
spot defects (DSD's) occur in:
a.
Non-semiconductor LASER
b.
Fiber LASER
c.
Glass fiber LASER
d.
Injection LASER